Endocytosis of prion protein is required for ERK1/2 signaling induced by stress-inducible protein 1
Endocytosis of prion protein is required for ERK1/2 signaling induced by stress-inducible protein 1
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DOI：
10.1523/jneurosci.1701-08.2008
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发表时间：
2008-06-25
影响因子：
5.3
通讯作者：
Prado, Marco A. M.
中科院分区：
文献类型：
--
作者：
Caetano, Fabiana A.;Lopes, Marilene H.;Prado, Marco A. M.
分泌的辅助伴侣 STI1 通过与细胞表面的细胞朊病毒 (PrPC) 相互作用，触发蛋白激酶 A (PKA) 和 ERK1/2 信号传导的激活，从而产生神经保护作用并增加神经突发生。在这里，我们研究了 STI1 是否触发 PrPC 贩运，并测试了该过程是否控制 PrPC 依赖性信号传导。我们发现 STI1（而非无法结合 PrPC 的 STI1 突变体）诱导 PrPC 内吞作用。 STI1 诱导的信号传导不会发生在缺乏内源性 PrPC 的细胞中；然而，PrPC 的异源表达重建了 PKA 和 ERK1/2 的激活。相比之下，缺乏内吞活性的PrPC突变体无法促进STI1诱导的ERK1/2激活，而它在相同条件下重建了PKA活性，这表明内吞作用在前一个过程中发挥了关键作用。 STI1 对 ERK1/2 的激活是短暂的，并且似乎取决于两种蛋白质在细胞表面或内化后不久的相互作用。此外，通过表达显性失活突变体来抑制动力活性，导致这些蛋白质在质膜上积累和共定位，表明这两种蛋白质都使用动力依赖性内化途径。这些结果表明 PrPC 内吞作用是调节参与神经突发生的 STI1 依赖性 ERK1/2 信号传导的必要步骤。
The secreted cochaperone STI1 triggers activation of protein kinase A (PKA) and ERK1/2 signaling by interacting with the cellular prion (PrPC) at the cell surface, resulting in neuroprotection and increased neuritogenesis. Here, we investigated whether STI1 triggers PrPC trafficking and tested whether this process controls PrPC-dependent signaling. We found that STI1, but not a STI1 mutant unable to bind PrPC, induced PrPC endocytosis. STI1-induced signaling did not occur in cells devoid of endogenous PrPC; however, heterologous expression of PrPC reconstituted both PKA and ERK1/2 activation. In contrast, a PrPC mutant lacking endocytic activity was unable to promote ERK1/2 activation induced by STI1, whereas it reconstituted PKA activity in the same condition, suggesting a key role of endocytosis in the former process. The activation of ERK1/2 by STI1 was transient and appeared to depend on the interaction of the two proteins at the cell surface or shortly after internalization. Moreover, inhibition of dynamin activity by expression of a dominant-negative mutant caused the accumulation and colocalization of these proteins at the plasma membrane, suggesting that both proteins use a dynamin-dependent internalization pathway. These results show that PrPC endocytosis is a necessary step to modulate STI1-dependent ERK1/2 signaling involved in neuritogenesis.